Multifunction reservoir for a secondary loop, climate control system and a secondary loop climate control system incorporating that multifunction reservoir

ABSTRACT

Secondary loop air conditioning and heat pump systems include a reservoir with a capsule holding a phase change material.

This application is a division of U.S. patent application Ser. No.15/815,112 filed on 16 Nov. 2017, the full disclosure of which isincorporated herein by reference.

TECHNICAL FIELD

This document relates generally to the climate control field and, moreparticularly, to a multifunction reservoir for a secondary loop climatecontrol system as well as to a secondary loop climate control systemincorporating that multifunction reservoir and adapted for use in, forexample, motor vehicles. Secondary loop climate control systems includeboth secondary loop air conditioning systems and secondary loop heatpump systems.

BACKGROUND

This document relates to a new and improved multifunction reservoir fora secondary loop climate control system such as a secondary loop airconditioning system or a secondary loop heat pump system. Themultifunction reservoir incorporates a capsule containing a phase changematerial (PCM). As a result, the multifunction reservoir provides acoolant storage function, a surge tank function to prevent pressurespikes, an air ventilation function, and now a thermal storage functionwithout adding a separate component with dedicated thermal storagefunction to the climate control system.

SUMMARY

In accordance with the purposes and benefits described herein, a new andimproved multifunction reservoir is provided for a secondary loopclimate control system. That multifunction reservoir comprises a coolantvessel, one or more capsules held in the coolant vessel and a PCMcontained in each capsule.

The multifunction reservoir may further include an inlet port and anoutlet port on the coolant vessel. In addition, the multifunctionreservoir may further include a modulating functionality feature at oneof the inlet port and the outlet port in order to allow adjustment ofthe coolant flow rate. That modulating functionality feature may be apulse width modulation solenoid valve.

The PCM provided in the capsule may be substantially any phase changematerial suitable for the intended purpose of thermal storage for asecondary loop climate control system. Dependent upon the temperaturerange over which the phase transition occurs, PCMs may be divided intothree main groups: a) Low temperature materials with phase transitiontemperature below 15 degree Celsius, for example in air conditioningapplications, b) Mid temperature materials with phase transitiontemperature between 15 to 90 degree Celsius, for example in solar orheat pump applications, and c) High temperature materials with phasetransition temperature above 90 degree Celsius, for example in aerospaceapplications. A low temperature PCM could be salt hydrates such asLiClO₃.3H₂O, or paraffins such as n-Tetradecane (paraffin 14-carbons)and n-Pentadecane (paraffin 15-carbons). A mid temperature PCM couldalso be salt hydrates such as CaCl₂.6H₂O, or paraffins such asn-Docozane (paraffin 22-carbons) and n-Oktacozane (paraffin 28-carbons).A high temperature PCM could be inorganic compounds such as AlCl₃ orNaNO₃.

The capsule includes an outer wall made preferably from a thermallyconductive and stable material. For example, that material may beselected from a group of metallic materials such as aluminum, copper,stainless steel, and carbon steel.

In accordance with an additional aspect, a secondary loop airconditioning system is provided. That secondary loop air conditioningsystem comprises a refrigerant loop, adapted to circulate a refrigerantbetween a compressor, a condenser, an expansion device and a chiller,and a coolant loop adapted to circulate a coolant between the chiller, apump, a first cooler and a reservoir having an integrated phase changematerial feature.

That reservoir may comprise a coolant vessel and the PCM feature maycomprise at least one capsule held in the coolant vessel and a PCMcontained in each capsule.

The secondary loop air conditioning system may further include an inletport and an outlet port in the coolant vessel and a modulatingfunctionality feature at one of the inlet port and the outlet port toadjust the coolant flow rate. That modulating functionality feature maybe achieved via a pulse width modulating solenoid valve. The PCM may besubstantially any phase change material suitable for low temperatureapplication, e.g. Paraffin 14-carbons. The capsule may include an outerwall made preferably from a thermally conductive and stable material,e.g. metallic materials such as aluminum, copper, stainless steel, andcarbon steel.

The secondary loop air conditioning system may further include a secondcooler in the coolant loop. The two coolers may provide an airconditioning function to two different zones of a motor vehicle.

In accordance with yet another aspect, a secondary loop heat pump systemis provided. That secondary loop heat pump system comprises a firstfour-way valve, a second four-way valve, a cooling circuit incommunication with the first four-way valve and the second four-wayvalve and a heating circuit in communication with the first four-wayvalve and the second four-way valve. The cooling circuit includes a coldsource, a first reservoir, a first heat exchanger and a first pump. Theheating circuit includes a heat source, a second reservoir, a secondheat exchanger and a second pump. The first reservoir in the coolingcircuit includes a first phase change material feature. The secondreservoir in the heating circuit includes a second phase change materialfeature.

The first reservoir may comprise a first coolant vessel. The first phasechange material feature may comprise a first capsule held in the firstcoolant vessel and a first phase change material contained in the firstcapsule. The second reservoir may comprise a second coolant vessel. Thesecond phase change material feature may comprise a second capsule heldin the second coolant vessel and a second phase change materialcontained in the second capsule. The first phase change material may bea low temperature PCM such as paraffin 14-carbons. The second phasechange material may be a mid temperature PCM such as paraffin28-carbons.

In the following description, there are shown and described severalpreferred embodiments of a multifunction reservoir, a secondary loop airconditioning system incorporating the multifunction reservoir and asecondary loop heat pump system also incorporating the multifunctionreservoir. As it should be realized, the multifunction reservoir, thesecondary loop air conditioning system and the secondary loop heat pumpsystem are capable of other, different embodiments and their severaldetails are capable of modification in various, obvious aspects allwithout departing from the multifunction reservoir, secondary loop airconditioning system and secondary loop heat pump system as set forth anddescribed in the following claims. Accordingly, the drawings anddescriptions should be regarded as illustrative in nature and not asrestrictive.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

The accompanying drawing figures incorporated herein and forming a partof the specification, illustrate several aspects of the multifunctionreservoir, the secondary loop air conditioning system and the secondaryloop heat pump system and together with the description serve to explaincertain principles thereof.

FIG. 1 is a schematic illustration of the multifunction reservoir thatis adapted for use in a secondary loop climate control system such as asecondary loop air conditioning system or a secondary loop heat pumpsystem.

FIG. 2 is a schematic illustration of a capsule insert for themultifunction reservoir.

FIG. 3 is a schematic perspective illustration of a secondary loop airconditioning system incorporating a multifunction reservoir of the typeillustrated in FIG. 1.

FIG. 4 is a schematic block diagram of a secondary loop heat pump systemincorporating two multifunction reservoirs of the type illustrated inFIG. 1: a first multifunction reservoir being provided in the coldcoolant loop and a second multifunction reservoir being provided in thehot coolant loop.

FIG. 5a illustrates the secondary loop heat pump system of FIG. 4operating in a cooling mode.

FIG. 5b illustrates the secondary loop heat pump system of FIG. 4operating in a heating mode.

FIG. 5c illustrates the secondary loop heat pump system of FIG. 4operating in a de-humidification and reheat mode.

Reference will now be made in detail to the present preferredembodiments of the multifunction reservoir, the secondary loop airconditioning system and the secondary loop heat pump system, examples ofwhich are illustrated in the accompanying drawing figures.

DETAILED DESCRIPTION

Reference is now made to FIG. 1 which schematically illustrates the newand improved multifunction reservoir 10. That multifunction reservoir 10is particularly adapted for use in a secondary loop climate controlsystem such as the secondary loop air conditioning system 12 illustratedin FIG. 3 and the secondary loop heat pump system 14 illustrated inFIGS. 4 and 5 a-5 c.

As illustrated in FIG. 1, the multifunction reservoir 10 includes acoolant vessel 16 formed from any appropriate material suited to hold acoolant C for a climate control system while resisting corrosion andproviding reliable operation over an extended service life in a motorvehicle environment. The multifunction reservoir 10 also includes acapsule 18 held within the coolant chamber 20 of the coolant vessel 16.A phase change material 22 is provided within the capsule 18.

More specifically, the phase change material 22 may be any PCM suitablefor use in a climate control system environment including, for example,paraffins or salt hydrates. That material may be selected dependent uponthe operating conditions of the climate control system and phasetransition temperature of PCMs. For example, paraffin 14-carbons has aphase change temperature of about 6 degree Celsius and is suitable foruse in a multifunction reservoir 10 utilized in the cold coolant loop ofa secondary loop climate control system. In contrast, paraffin28-carbons has a phase change temperature of about 61 degree Celsiusmaking it suitable for use in a multifunction reservoir 10 used in thehot coolant loop of a secondary loop climate control system. The capsule18 includes an outer wall 24, preferably made from a material that isthermally conductive, stable and resistant to corrosion from the coolantC held in the coolant vessel 16 and the phase change material 22 held inthe capsule. For example, the outer wall 24 may be made from metallicmaterials such as aluminum, copper, stainless steel, and carbon steel.

The multifunction reservoir 10 illustrated in FIG. 1 includes a singlecapsule 18 holding a phase change material 22. Here it should be notedthat more than one capsule 18 may be provided in the coolant chamber 20of the coolant vessel 16. FIG. 2 illustrates a multi-capsule insert 30including three capsules 32 all holding a phase change material 22. Thethree capsules 32 are all fixed to a support or base 33 to maintainspacing between the capsules 32 to accommodate the flow of coolant Cbetween and around the capsules for the most efficient heat exchange. Asshould be appreciated, the multi-capsule insert 30 may be substitutedfor the capsule 18 illustrated in FIG. 1. Here it should also be notedthat the heat exchange material provided in each of the capsules 32 maybe the same or may be different with different phase changetemperatures. The PCM selected for each of the capsules 32 is a productof the design parameters and performance requirements required of thesecondary loop climate control system as adapted for a givenapplication.

As further illustrated in FIG. 1, the multifunction reservoir 10includes an inlet port 34 and an outlet port 36 for circulating thecoolant C into and out of the coolant vessel 16. In the illustratedembodiment, the inlet port 34 is provided in the coolant vessel 16 neara midline while the outlet port 36 is provided closer to the bottom 17of the vessel.

A modulating functionality feature 38 may be provided at one of theinlet port 34 and the outlet port 36 in order to adjust the coolant flowrate. In the illustrated embodiment, the modulating functionalityfeature 38 is provided in the outlet port 36. The modulatingfunctionality feature 38 may take the form of a flow control valve ofany appropriate structure including, for example, a pulse widthmodulating solenoid valve allowing for adjustment of the coolant flowrate from the multifunction reservoir 10 to be achieved via frequencycontrol or position control. More specifically, a correlation can bedeveloped between frequency (or openness) of the valve and a coolantflow rate with the desired flow rate being determined by the requiredheat exchanger capacity, heat exchanger geometries, air inlet andcoolant inlet conditions.

Reference is now made to FIG. 3 illustrating the secondary loop airconditioning system 12. The secondary loop air conditioning system 12comprises a refrigerant loop 40 adapted to circulate a refrigerant suchas R134a, R1234yf, R152a, or R744 (CO₂), between a compressor 42, acondenser 44, an expansion device 46 and a chiller 48. Action arrows Aillustrate the circulation of the refrigerant through the refrigerantloop 40 by the compressor 42.

The secondary loop air conditioning system 12 also includes a coolantloop 50 adapted to circulate a coolant, such as ethylene glycol andwater mixture, or propylene glycol and water mixture, between thechiller 48, a pump 52, a first cooler 54 and a reservoir 56 of a typeillustrated in FIG. 1 having an integrated phase change material feature57, such as a capsule 18 containing a phase change material 22. Actionarrows B illustrate the circulation of the refrigerant through thecoolant loop 50 by the pump 52.

More specifically, refrigerant is compressed in the compressor 42 to ahigh temperature, high pressure vapor and enters the condenser 44 whereit is cooled through heat exchange with the ambient air circulating overthe condenser to low temperature, high pressure refrigerant, preferablyin pure liquid. The resulting low temperature, high pressure refrigerantexiting the condenser 44 passes through the expansion device 46 whichexpands the refrigerant to low temperature, low pressure vapor liquidmixture. The refrigerant mixture then evaporates in the chiller 48 dueto heat absorption from the coolant circulated in the coolant loop 50and exits as low temperature, low pressure vapor. The low temperature,low pressure refrigerant vapor is then returned back to the compressor42 to again begin the refrigerant cycle.

In the coolant loop 50, coolant from the reservoir 56 is pumped by thepump 52 to the chiller 48 for heat exchange with the refrigerant. Heatis transferred from the coolant to the refrigerant in the chiller 48.Chilled coolant discharged from the chiller 48 is delivered to thecooler 54. Air circulating through the heating, ventilating and airconditioning (HVAC) case 58 of the air conditioning system is in heatexchange relationship with the coolant in the cooler 54. As a result,cooled air is circulated into the passenger compartment of the motorvehicle. Following heat exchange with the air, the coolant is dischargedfrom the cooler 54 and returned to the reservoir 56 including theintegrated phase change material feature 57. Here it should beappreciated that the reservoir 56 provides four separate functions: (1)coolant storage, (2) surge tank function to prevent pressure spikes inthe coolant loop, (3) ventilation function to discharge air bubbles inthe coolant loop to outside environment, and (4) thermal storage throughheat exchange with the phase change material 22 of the integrated phasechange material feature 57.

Where the reservoir 56 includes a modulating functionality feature 38,the flow rate of coolant from the reservoir 56 to the pump 52 may becontrolled in a desired manner.

Reference is now made to FIG. 4, illustrating one possible embodiment ofsecondary loop heat pump system 14. Secondary loop heat pump system 14includes a first four-way valve 60, a second four-way valve 62, acooling circuit 64 and a heating circuit 66.

More specifically, the cooling circuit 64 is provided in communicationwith the first four-way valve 60 and the second four-way valve 62.Further, the cooling circuit 64 includes a cold source 68, such as thechiller of a refrigerant circuit, a first reservoir 70 that may beidentical to the multifunction reservoir 10 illustrated in FIG. 1, afirst heat exchanger 72 to provide heat exchange between the coolant inthe cooling circuit 64 and the air being circulated through thepassenger cabin of the motor vehicle and a first pump 74. The heatingcircuit 66 is also provided in communication with the first four-wayvalve 60 and the second four-way valve 62. The heating circuit 66includes a heat source 76 for heating the coolant, a second reservoir 78that may be identical to the multifunction reservoir 10 illustrated inFIG. 1, a second heat exchanger 80 for heat exchange between the coolantand the air being circulated through the passenger compartment of themotor vehicle and a second pump 82 for circulating coolant through theheating circuit 66. The integrated phase change material feature 83provided in the first reservoir 70 of the cooling circuit 64incorporates a low temperature PCM appropriate for a cooling circuit.Such a phase change material may be, for example, paraffin 14-carbons.In contrast, the second reservoir 78 in the heating circuit 66incorporates an integrated phase change material feature 85 having a midtemperature PCM appropriate for a heating circuit such as paraffin28-carbons.

FIG. 5a illustrates operation of the secondary loop heat pump system 14in cooling mode. As illustrated, the first pump 74 pumps coolant fromthe first reservoir 70 to the cold source 68 in order to remove heatfrom the coolant which is then pumped from the cold source through thefirst four-way valve 60 to the first heat exchanger 72. There, heat isremoved from the air being circulated into the passenger cabin in orderto provide desired cooling to the motor vehicle occupants. The warmedcoolant is then pumped through the second four-way valve 62 back to thefirst reservoir 70 completing one loop through the cooling circuit 64.The coolant continues to move through the cooling circuit 64 in thismanner (note action arrows C) until the cooling mode is terminated.

Reference is now made to FIG. 5b illustrating operation of the secondaryloop heat pump system 14 in heating mode. More specifically, coolantfrom the second reservoir 78 is pumped by the second pump 82 to the heatsource 76 for heat exchange. The heated coolant then travels from theheat source 76 through the second four-way valve 62 to the second heatexchanger 80 where the coolant is in heat exchange with the air beingcirculated through the passenger cabin of the motor vehicle. As aresult, that air is heated to warm the occupants of the passenger cabin.The coolant discharged from the second heat exchanger 80 is pumped bythe pump 82 through the first four-way valve 60 and then returned to thesecond reservoir 78 thereby completing one full cycle of the heatingcircuit 66. This movement of coolant continues in this manner (noteaction arrows D) until the heating mode is terminated.

Reference is now made to FIG. 5c illustrating operation of the secondaryloop heat pump system 14 in dehumidification and reheat mode. Coolant ismoving through the cooling circuit 64 in the same manner as thatdescribed above in FIG. 5a with respect to the cooling mode (note actionarrows C) and coolant is moving through the heating circuit 66 in thesame manner as that described above in FIG. 5b with respect to theheating mode (note action arrows D). As a result, air being directedinto the passenger compartment of the motor vehicle first comes in heatexchange contact with the first heat exchanger 72. At this point the airis cooled and dehumidified. Next, the air passes in heat exchangerelationship through the second heat exchanger 80. As a result the airis heated to provide dry warming comfort to passengers in the passengercompartment. Such air is particularly useful in defogging or deicing awindshield.

The multifunction reservoir 10, secondary loop air conditioning system12 and secondary loop heat pump system 14 described herein provide anumber of benefits and advantages. The multifunction reservoir 10integrates a phase change material feature 57, 83, 85 into a secondaryloop system and, more particularly, the reservoir 56, 70, 78 of thesecondary loop system without introducing a new and separate componentinto the system. As a result, the multifunction reservoir 10, 56, 70, 78not only provides traditional coolant storage and surge tankfunctionality but also allows for and provides thermal storage forbetter comfort and climate control system operation under substantiallyany foreseeable operating conditions. Where the multifunction reservoir10 incorporates a modulating functionality feature 38, it is possible tofully control coolant flow while utilizing a fixed speed coolant pump52, 74, 82 and also eliminating the need for a shutoff valve in thecircuit.

The secondary loop heat pump system 14 illustrated in FIG. 4 includesfirst and second reservoirs 70, 78 having integrated phase changematerial features 83, 85 providing more efficient and effectiveoperation of both the cooling circuit 64 and the heating circuit 66.

The foregoing has been presented for purposes of illustration anddescription. It is not intended to be exhaustive or to limit theembodiments to the precise form disclosed. Obvious modifications andvariations are possible in light of the above teachings. For example,the capsule 18 may be provided in any desired shape and may be providedin any desired number. The four-way valves 60, 62 may be replaced bymultiple one-way, two-way, or three-way valves. All such modificationsand variations are within the scope of the appended claims wheninterpreted in accordance with the breadth to which they are fairly,legally and equitably entitled.

What is claimed:
 1. A secondary loop air conditioning system,comprising: a refrigerant loop adapted to circulate a refrigerantbetween a compressor, a condenser, an expansion device and a chiller; acoolant loop adapted to circulate a coolant between said chiller, apump, a first cooler and a reservoir having an integrated phase changematerial feature, wherein said reservoir comprises a coolant vessel andsaid integrated phase change material feature comprises one or morecapsules and a phase change material in said one or more capsules, andwherein the coolant vessel is configured to hold at least said one ormore capsules; an inlet port and an outlet port in said coolant vessel,wherein said inlet port is disposed near a midline of the coolant vesseland said outlet port is generally disposed closer to a bottom of thecoolant vessel; and a modulating functionality feature at one of saidinlet port and said outlet port to adjust coolant flow rate, whereinsaid modulating functionality feature is a solenoid valve configured toadjust the coolant flow rate through pulse width modulation of a controlsignal, and wherein a frequency of the pulse modulation is determined byat least a heat exchanger capacity, a heat exchanger geometric profile,said inlet port, and an air inlet.
 2. The secondary loop airconditioning system of claim 1, wherein said phase change material hasphase change temperature below 15 degree Celsius.
 3. The secondary loopair conditioning system of claim 2, wherein said phase change materialis selected from a first group of materials consisting of paraffins orsalt hydrates.
 4. The secondary loop air conditioning system of claim 3,wherein each of the one or more capsules includes an outer wall madefrom a material selected from a second group of metallic materialsconsisting of aluminum, copper, stainless steel, and carbon steel. 5.The secondary loop air conditioning system of claim 1, further includinga second cooler in said coolant loop to provide an air conditioningfunction to two different zones of a motor vehicle.
 6. The secondaryloop air conditioning system of claim 1, wherein said phase changematerial has phase change temperature below 15 degree Celsius.
 7. Thesecondary loop air conditioning system of claim 1, wherein said phasechange material is selected from a first group of materials consistingof paraffins or salt hydrates.
 8. The secondary loop air conditioningsystem of claim 1, wherein each of the one or more capsules includes anouter wall made from a material selected from a second group of metallicmaterials consisting of aluminum, copper, stainless steel, and carbonsteel.
 9. A secondary loop air conditioning system, comprising: arefrigerant loop adapted to circulate a refrigerant between acompressor, a condenser, an expansion device and a chiller; a coolantloop adapted to circulate a coolant between said chiller, a pump, afirst cooler and a reservoir having an integrated phase change materialfeature; and an inlet port and an outlet port in said coolant vessel anda modulating functionality feature at one of said inlet port and saidoutlet port to adjust coolant flow rate, wherein said modulatingfunctionality feature is a solenoid valve configured to adjust thecoolant flow rate through pulse width modulation of a control signal,and wherein a frequency of the pulse width modulation is determined byat least a heat exchanger capacity, a heat exchanger geometric profile,said inlet port, and an air inlet.
 10. The secondary loop airconditioning system of claim 9, wherein said reservoir comprises acoolant vessel and said integrated phase change material featurecomprises a plurality of capsules coupled to a base of the coolantvessel and held in said coolant vessel, and wherein a plurality of phasechange materials are in said plurality of capsules, and wherein theplurality of capsules are spaced apart so as to allow for a flow of thecoolant.
 11. The secondary loop air conditioning system of claim 10,wherein said plurality of phase change materials further comprise afirst phase change material that is selected from a first group ofmaterials consisting of paraffins or salt hydrates, a second phasechange material that is either selected from a first group of materialsconsisting of paraffins or salt hydrates or a second group of materialsconsisting of aluminum chloride or sodium nitrate, and a third phasechange material that is either selected from a first group of materialsconsisting of paraffins or salt hydrates or a second group of materialsconsisting of aluminum chloride or sodium nitrate, and wherein saidplurality of capsules further comprise a first capsule configured tohouse said first phase change material, a second capsule configured tohouse said second phase change material, and a third capsule configuredto house said third phase change material.
 12. The secondary loop airconditioning system of claim 9, further comprising an inlet port and anoutlet port in said coolant vessel, and wherein said inlet port isdisposed near a midline of the coolant vessel and said outlet port isdisposed closer to a bottom of the coolant vessel.